1. Field of the Invention
This technology relates to an oscillator circuit, and in particular an oscillator circuit with a hysteresis circuit, such as a series of cross-coupled inverters, and separately in particular to the inclusion of multiple current sources to simplify the prediction of the oscillator frequency.
2. Description of Related Art
Current controlled ring oscillators, with a series of inverters powered by current sources, have a frequency which is difficult to predict, and have a slow transient. The slow transient and the difficulty of predicting the output frequency occur, because despite the inclusion of current sources, the charging and discharging current of an output node in the current controlled oscillator is not determined by a simple relationship to the size of the current sources. Instead, the current controlled ring oscillators has an output frequency which is a complicated and slow function of the sizes of the PMOS and NMOS transistors of the neighboring inverters, mobility, input voltage, etc.